"Lightning surge damage to Ethernet and POTS ports connected to inside wiring" http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=3D6842005
A summary of the paper: http://incompliancemag.com/article/lightning-surge-damage-to-ethernet-and-pots-ports-connected-to-inside-wiring/ a slide deck on the same subject, by the same author: http://www.atis.org/peg/docs/2015/LightningSurgeDamage_JRandolph.pdf In which: > Interestingly, some generic replacement power supplies purchased on the Internet showed breakdown levels as low as 3 kV. Internal inspection revealed that the isolation barriers in these supplies were not compliant with [10]. These non-compliant supplies had no safety markings from independent labs, although they did have the CE marking for manufacturer’s self-declaration in Europe. Which is to say cheap far-eastern wall warts are not compliant, though claiming to be. > At present there is no evidence of non-compliant power supplies being used by name brand manufacturers of routers and cordless phones. "Well, obviously it's not meant to be taken literally; it refers to any manufacturers of dairy products." [1] But here's the important bottom line: > The key point here is that a high current, fast rise time surge on the AC mains can interact with the inductance of the ground wire to create a high voltage common mode surge on every cable that is connected to the surge protector. In some sense, the surge protector takes a surge on the AC mains and “broadcasts” it onto every cable that is connected to the surge protector. This happens despite the fact the surge protector has been installed correctly and the ground wire of the AC mains outlet is connected properly. In other words, your ground wire won't help you. Check the slide deck (and paper), it can be that the ground potential has risen. I'll add that inductive coupling is a function of the rate of change rather than the peak current. So when di/dt is a small fraction of infinity, it doesn't really matter much that your inductor coil is a stretch of wire five meters away ... it's going to get a big spike of current and the teeny tiny little transistors in your equipment are going to arc over. A small puff of smoke will appear. If you're unlucky, a fire will shortly (narf) follow. Surge protectors have several practical failures: 1 - they are rated for a certain amount of energy, and a big strike overwhelms that, so you're done. 2 - they are rated for that amount of energy over their service lifetime, which means that come the big storm your five-year-old surge protector has actually sacrificed itself to a thousand little surges that you never noticed over the time it's been in service. 3 - they have a response curve that makes them more suitable for lower di/dt or dv/dt spikes ... this makes them a good protection for spikes that originate far away and get their sharp edges worn off as they travel across the network, not so much for close hits. For extra credit: Who did some of the important early research on lightning effects? Why, Mr Steinmetz, of course. https://en.wikipedia.org/wiki/Charles_Proteus_Steinmetz tl;dr: your multiport surge protectors are a prime suspect. Jim [1] https://en.wikiquote.org/wiki/Monty_Python%27s_Life_of_Brian On Mon, Jul 25, 2016 at 4:41 PM, Karl Fife <karlf...@gmail.com> wrote: > The 6th Ethernet port (em5) on my Lanner fw-7541D died Saturday night > during the electrical storm. Just the one port. > > Apparently fried, apparently by an electrical anomaly. > > Now, the link light is always on (dimly lit), whether populated or not, > and neither the POST, nor the OS detects the presence of the fifth port. > > Interesting how it failed: The fried port 'simply' broke connectivity for > the interface's LAN segment. Everything else continued to work. I kinda > didn't believe the report that Internet was out for the one LAN, since the > other was not. After some testing, I found the system would not come up > after reboot because it had gone into port reassignment mode since the > config made reference to a non-existent interface. > > I edited the config in VI to de-reference the interface, and All's well. > > I really like this Lanner hardware, and would like to keep it in service. > Ideally I'd like to fix the (now dead) spare port so that I still have a > spare. > > Can anyone tell me what's component is typically fried in this scenario? > Is it the NIC controller chip itself? I'm guessing it's not, rather I'm > guessing it's just the big, blocky Ethernet Isolation transformer/amplifier > that's been fried. I'm also guessing that the reason the system is still > functional (at all) is because the little dude did its job. I know it's a > long shot, but I'd like to hear if anyone has ever repaired a fried > Ethernet port on a motherboard. > > Also ironic, everything's very well grounded with a dedicated earth-ground > via #6 AWG except the one (damned) switch that services that one (damned) > LAN. I imagine if I'd gone to the trouble of running a dedicated ground to > that switch, it may not have sunk the spike. Any experience or war stories > in this arena appreciated as well. Memo to myself: Run fiber to switches > on different power/earth. > > -Karl > _______________________________________________ > pfSense mailing list > https://lists.pfsense.org/mailman/listinfo/list > Support the project with Gold! https://pfsense.org/gold > _______________________________________________ pfSense mailing list https://lists.pfsense.org/mailman/listinfo/list Support the project with Gold! https://pfsense.org/gold
